This invention relates to methods and apparatus for making multiple-component smoking articles, especially such articles having at least one component which is relatively rigid and/or brittle and which therefore cannot be processed in the same way that the usual relatively elastic components of smoking articles are processed.
There is growing interest in rodlike smoking articles in which the tobacco is not burned but is merely heated to cause it to release its flavors. One possible construction of such smoking articles comprises (1) a distal heat and flavor generator, (2) a proximal portion including a plug of filter material at the extreme proximal end and possibly a short tobacco segment on the distal side of the filter plug, and (3) a hollow tube interconnecting the distal and proximal components. All of these components are typically cylindrical, coaxial, and of approximately the same outer diameter. One or more outer wrappings (e.g., of paper or the like) are used to hold all of these components together and/or to give the finished article the external appearance of a conventional smoking article (e.g., a conventional cigarette).
Among the possible heat generators for smoking articles of the type described above are generators which comprise a perforated aluminum tube containing a combustible carbon rod. Unlike most prior smoking article components, such tubes containing carbon rods are radially relatively rigid and fragile. This means that smoking articles including such tubes cannot be assembled by passing them through a garniture which relies on radial compressibility of the components being processed. It also means that excessive radially directed force must not be used at any time during the assembly of smoking articles including such tubes because of the danger that the tube will collapse or lose its roundness and/or that the carbon rod will break.
Another problem associated with assembling smoking articles including an aluminum tube containing a carbon rod is that it would be extremely difficult or impossible to cut the smoking article transversely in the vicinity of the tube. On the other hand, it is highly desirable to have the distal end of the overwrap completely cover the distal end of the tube with no excess overwrap extending beyond the distal end of the tube. If the overwrap is too short (i.e., if it does not completely cover the tube), the product may not have an acceptable appearance. If the overwrap is too long (i.e., if it extends beyond the distal end of the tube), the excess overwrap may flame up unacceptably when the product is lit by the consumer. Yet the difficulty or impossibility of cutting the smoking article transversely adjacent to the tube makes it extremely difficult to achieve precise alignment of the distal end of the overwrap with the distal end of the tube.
Although perforated aluminum tubes have been referred to for convenience in the foregoing discussion, it will be apparent that tubes of other metals or materials are also possible and would present similar problems. For example, the tube could be a hollow ceramic tube.
In view of the foregoing, it is an object of this invention to provide methods and apparatus for assembling smoking articles of the type described above.
It is a more particular object of the invention to provide methods and apparatus for assembling smoking articles including radially rigid and/or fragile components which avoid the use of excessive radial force during assembly of the articles.
It is another more particular object of this invention to provide methods and apparatus for more precisely aligning the edge of a smoking article overwrap with the end of the smoking article component being overwrapped without the need to cut the smoking article transversely adjacent that end after it has been overwrapped.